Thanks for the advice much appreciated. I have been looking for a couple of days and came across canna terra professional. Link below.
Is this a good starting point?
Is there no soil then that can be purchased that will go the whole length of the grow?
https://www.growland.co.uk/Canna-Terra-Professional-50l?gclid=CJbgsv3OqMwCFeYK0wodQpED7w?mt=1
Is this a good starting point?
Yes, but it won't take you the whole way. You could start with this and amend it with extra nutrients, but I think you'd be guessing at how much to add because of whats already in there.
Is there no soil then that can be purchased that will go the whole length of the grow?
Simple answer, no, not in the UK
I have recently found this 'supersoil nutrient pack' on ebay in the uk, but you would need to add this to a base soil and in most peoples opinion on here the recipe is a little outdated and better nutrients could be used.
http://www.ebay.co.uk/itm/Super-soil-home-mix-ph-nutrients-soil-improver-super-for-flowers-and-herbs-/301937887861?hash=item464ce68a75:g:7g8AAOSwqYBWmnDx
You could get the canna soil and mix this in at 50g per 10L of soil. You would then have to let the soil sit for at least 4-5 weeks before you could use it. This should get you all the way, but there's no guarantee's on anything, too many variables.
I have also now found UK sources for all ingredients in the 'Coot' soil mix. It may work out a little more expensive to start up, because of the size of the nutrient packs you would have to buy, but you won't be buying anything else for a long time, they'll last you years. In theory you can mix your own 'Coot' soil and plant straight into it and IMHO, this would be your best option. It'd take me a little time to find all the links for ya, so read up on Coot's mix and let me know if you wanna go that way